Hultin said studies show that vegetarians (and even more so, vegans) routinely have lower body weights. That's because plant-based foods like veggies are high in fibre, and research shows that women who followed a higher-fibre diet were at a reduced likelihood of having an increased waist circumference. Try eating a more plant-based diet, focusing on veggies, whole grains, and plant proteins such as beans, nuts, seeds, and soy products.